1. Field of the Invention
The present invention relates to a honeycomb structure and, more specifically, to a honeycomb structure functioning not only as a catalyst carrier but also as a heater.
2. Description of Related Art
There has conventionally been used a cordierite honeycomb structure having a catalyst loaded thereon for treating harmful substances in exhaust gas discharged from an automobile engine. In addition, there is known the use of a honeycomb structure formed of a silicon carbide sintered body for purification of exhaust gas (see, e.g., Patent Document 1).
In the case of treating exhaust gas by a catalyst loaded on a honeycomb structure, it is necessary to raise the temperature of the catalyst up to predetermined temperature. However, since the catalyst has low temperature at the time of engine start-up, there is a problem of insufficient purification of exhaust gas.
Therefore, there is investigated a method of raising temperature of exhaust gas by setting a metal heater on the upstream side of the honeycomb structure having a catalyst loaded thereon (see, e.g., Patent Document 2).